1. The Field of the Invention
The present invention relates generally to optical transceivers. More specifically, the present invention relates to optical transceivers that perform persistent logging of its own operational information.
2. Background and Relevant Art
Computing and networking technology have transformed our world. As the amount of information communicated over networks has increased, high speed transmission has become ever more critical. Many high speed data transmission networks rely on optical transceivers and similar devices for facilitating transmission and reception of digital data embodied in the form of optical signals over optical fibers. Optical networks are thus found in a wide variety of high speed applications ranging from as modest as a small Local Area Network (LAN) to as grandiose as the backbone of the Internet.
Typically, data transmission in such networks is implemented by way of an optical transmitter (also referred to as an electro-optic transducer), such as a laser or Light Emitting Diode (LED). The electro-optic transducer emits light when current is passed there through, the intensity of the emitted light being a function of the current magnitude. Data reception is generally implemented by way of an optical receiver (also referred to as an optoelectronic transducer), an example of which is a photodiode. The optoelectronic transducer receives light and generates a current, the magnitude of the generated current being a function of the intensity of the received light.
Various other components are also employed by the optical transceiver to aid in the control of the optical transmit and receive components, as well as the processing of various data and other signals. For example, such optical transceivers typically include a driver (e.g., referred to as a “laser driver” when used to drive a laser signal) configured to control the operation of the optical transmitter in response to various control inputs. The optical transceiver also generally includes an amplifier (e.g., often referred to as a “post -amplifier”) configured to perform various operations with respect to certain parameters of a data signal received by the optical receiver. A controller circuit (hereinafter referred to the “controller”) controls the operation of the laser driver and post amplifier.
The operation of optical transceiver is susceptible to its operating environment and to its other operational parameters. One obvious example is the laser bias current. If the transmitter bias current drifts upwards or downwards, a variation in the optical intensity generated by the transmitter may be expected. The transmitted optical power and the received optical power are also important operational parameters. The supply voltage level provided to the optical transceiver also affects its performance.
In addition, temperature can change the operating characteristics of the optical transmitter itself. In particular, the wavelength output of a laser may drift from approximately 0.3 nanometers (nm) to approximately 0.6 nm for every one degree Celsius change in temperature. Since lasers generate heat during operation, this can have a significant effect upon the operation of the laser. Wavelength variations can cause crosstalk, where one transmission becomes confused with another. Furthermore, varying wavelengths due to varying laser temperature may cause different fiber attenuations. Accordingly, laser temperature and wavelength have great influence over the proper operation of the optical transceiver.
High temperatures of the optical transceiver itself may cause temporary or even permanent malfunctioning of not just the laser, but the other electronic components within the optical transceiver. Accordingly, the temperature of the optical transceiver as a whole is also important to the operation of the optical transceiver.
In order to provide proper cooling or heating to the optical transceiver and/or laser, Thermo Electric Coolers (TECs) are often employed, particularly in optical transceivers whose performance is highly temperature-dependent. Such TEC coolers heat or cool depending on the direction and magnitude of current applied to the TEC coolers. Accordingly, the TEC current is also an important operational parameter.
These various parameters (e.g., laser bias current, transmit power, receive power, supply voltage, laser wavelength, laser temperature, transceiver temperature, and TEC current, and the like) are thus important to the operation of the optical transceiver. However, after an optical transceiver malfunctions, it is often difficult to diagnose what the problem has been since there is no conventional mechanism for persistently logging important events that may give an indication as to why the transceiver malfunctioned. For example, if an optical transceiver has an upper temperature rating of 85 degrees Celsius, the optical transceiver may malfunction or even permanently break if its temperature reaches 110 degrees Celsius. Yet, after the fact, it may be difficult to discover that the optical transceiver was subjected to improper temperatures.
Therefore, what would be advantageous is a mechanism for persistently logging events that are important to the operation of an optical transceiver so that these events may be later used to understand the conditions under which the optical transceiver operated.